1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, and a process cartridge and an electrophotographic apparatus including the electrophotographic photosensitive member.
2. Description of the Related Art
As an electrophotographic photosensitive member included in an electrophotographic apparatus, electrophotographic photosensitive members containing organic photoconductive substances have been earnestly developed. An electrophotographic photosensitive member generally contains a support and a photosensitive layer formed on the support and containing an organic photoconductive substance. Furthermore, the photosensitive layer is generally of a laminated type (a successive layer type) containing a charge-generating layer and a charge-transporting layer stacked in this order on the support.
In electrophotographic process, the surface of an electrophotographic photosensitive member is brought into contact with various materials including a developer, a charging member, a cleaning blade, paper and a transferring member (which are hereinafter sometimes generically designated as “contact members”). Therefore, one of characteristics required of an electrophotographic photosensitive member is reduction of image degradation derived from contact stress caused by these contact members. In particular, in accordance with recent improvement in the durability of an electrophotographic photosensitive member, further improvement is demanded in persistence of the effect of reducing image degradation derived from the contact stress and suppression of potential variation in repeated use.
With respect to persistent relaxation of the contact stress and suppression of potential variation in repeated use of an electrophotographic photosensitive member, International Publication No. WO2010/008095 proposes a method for forming a matrix-domain structure in a surface layer by using a siloxane resin in which a siloxane structure is incorporated into a molecular chain. This publication describes that the persistent relaxation of the contact stress and the suppression of potential variation in repeated use of an electrophotographic photosensitive member can be both attained by using a polyester resin having a specific siloxane structure incorporated thereinto.
Although the electrophotographic photosensitive member disclosed in International Publication No. WO2010/008095 attains both of the persistent relaxation of the contact stress and the suppression of potential variation in repeated use, further improvement is demanded in order to realize an electrophotographic apparatus operable at a higher speed and capable of producing a larger number of printed copies. As a result of study made by the present inventors, it has been revealed that further improvement can be achieved by allowing an electrophotographic photosensitive member to contain a specific compound in forming a matrix-domain structure.